1. Field of the Invention
The present invention is generally concerned with tactile sensors of the kind including at least one piezo-electric member under a control key accessible to the user and responsive to any depression of the control key by the user.
2. Description of the Prior Art
For example, tactile sensors of this kind constitute the control device or input device of certain devices, in particular certain electrical devices, such as on/off switches, changeover switches and dimmers.
They are also used in other devices, for example keypads.
The piezo-electric member is usually disposed between two metal electrodes which connect it to the electrical control circuit that it controls or, more generally, to an electrical circuit of any kind.
One of the problems encountered in the production of tactile sensors using a piezo-electric member of this kind is to hold it in position whilst leaving it sufficient freedom of movement to function.
In some implementations the piezo-electric member is mechanically located between its two electrodes, for example by placing it in a cavity in which it is duly peripherally confined.
However, implementations of this type usually involve the use of a non-negligible number of intermediate parts, to the detriment of efficiency and therefore of sensitivity.
In other implementations the electrodes are parts of conductive films between which the piezo-electric member must be inserted.
In practise, however, these implementations are subject to production engineering problems which usually lead to large overall size and/or high cost.
The present invention is more particularly directed to the situation in which the piezo-electric member is attached, for example glued, to one of the electrodes, referred to hereinafter for convenience only as the top electrode or forward electrode, while the other electrode, referred to hereinafter for convenience only as the bottom electrode, or rearward electrode, is attached to a support of any kind, for example the substrate of a printed circuit of any kind.
A general aim of the present invention is to provide an arrangement which, in this case, provides a simple and effective means of holding the piezo-electric member in place without compromising its effectiveness, and which also procures other advantages.